Apparatus for charging a blast furnace continuously



Nov. 4, 1969 H. COLIJN APPARATUS FOR CHARGING A BLAST FURNACE GONTINUOUSLY Filed June 6. 1967 INVENTOR. HENDRIX COL/J y Attorney United States Patent 3,476,374 APPARATUS FOR CHARGING A BLAST FURNACE CONTINUOUSLY Hendrik Colijn, Monroeville Borough, Pa., assignor to United States Steel Corporation, a corporation of Delaware Filed June 6, 1967, Ser. No. 643,870 7 Int. Cl. C21b 7/20 US. Cl. 266-27 Claims ABSTRACT OF THE DISCLOSURE The present invention relates generally to blast furnaces for smelting iron ore, limestone and coke, and more particularly to apparatus for continuously charging burden material into a blast furnace.

Prior to my invention, blast furnace charging was primarily a batch operation and the charging of the burden material into the furnace was accomplished using a system of two or more bells to distribute the burden in the furnace stack and to provide a pressure seal at the top thereof. The greatest disadvantage with this prior practice was that it permitted only intermittent charging operations. It did not prevent burden material segregation and, in fact, required layered burdcning of the furnace.

It is, accordingly, the primary object of my invention to provide apparatus whereby a continuous blast furnace burdcning operation may be conducted and which permits utilization of a pre-mixed (ore-stone-coke) burden, which eliminates layered burdcning of the furnace resulting in better control of the iron making process.

It is a more specific object of my invention to provide apparatus for continuously charging a blast furnace which substitutes for the conventional small bell and large bell and their respective hoppers, a pressure reducing hopper disposed at the top of the blast furnace stack, a surge hopper disposed on top of the pressure reducing hopper and communicating therewith, and a rotating charging hopper in the top of the surge hopper for receiving burden material from an endless belt conveyor and distributing it in a uniform manner in the surge hopper.

These and other objects will become more apparent after referring to the following specification and attached drawings in which:

FIGURE 1 is a vertical sectional view of the apparatus of the invention installed on the stack of a blast furnace;

FIGURE 2 is a cross-sectional view taken substantially along the line 11-11 of FIGURE 1;

FIGURE 3 is a cross-sectional view taken substantially along the line IIIIII of FIGURE 1;

FIGURE 4 is a cross-sectional view taken substantially along the line IVIV of FIGURE 1; and

FIGURE 5 is a vertical sectional view taken substantially along the line V--V of FIGURE 1.

Referring more particularly to the drawing, reference numeral 2 designates a blast furnace stack having a primary exhaust gas main 4 disposed around the upper portion thereof with gas outlets 6 spaced therearound. A pressure reducing hopper 8 having a restricted upper end 10, and a restricted annular throat 12 in its lower end is disposed on top of the stack 2. The primary gas exhaust main is disposed below the pressure reducing hopper. A spider bracing 14 disposed in the bottom of the hopper 8 is provided with a central gas chamber 16 having radially extending exhaust gas ducts 18 for conducting exhaust gases to the gas main 4 from the central area of the upper part of the stack 2. The gases enter the chamber 16 from the stack 2 through openings 19.

A skirt or bafiie 20 is disposed in the upper end of the stack 2 to prevent solids from entering the gas main 4. Ports 22 are provided in the lower portion of the skirt 20 and ports 24 are provided in the upper portion of the skirt for conducting exhaust gases to the gas main 4 from the peripheral area of the upper portion of the stack.

The annular throat 12 of the hopper 8 has an entry angle and exit angle each approximately 60 to the horizontal so as to insure smooth flow of materials from the hopper into the stack of the furnace.

The walls of the restricted upper end 10 of the pressure reducing hopper 8 extend downwardly and outwardly at an angle of approximately 60 to the horizontal to insure the free flow of material into the hopper.

A secondary exhaust gas main 26 is disposed around the upper portion of the pressure reducing hopper 8 for collecting exhaust gases to be emitted from outlets 28.

spaced around the main 26. Ports 30 in the upper end 10 of the hopper 8 conduct residual exhaust gases from the interior of the hopper to the secondary exhaust rnain 26.

The height of the pressure reducing hopper 8 is preferably suflicient to reduce the gas pressure in the upper portion of the hopper to an atmospheric level. With the average pre mixed burden material, the pressure drop is approximately one pound per square inch per four feet of burden material height. Thus, for a furnace operation at 5 p.s.i. top pressure, the pressure reducing hopper height should be approximately 20 feet. The secondary gas exhaust main is provided at the upper end of the hopper 8 to exhaust any gases remaining in the hopper that were not emitted via the primary gas main outlets 6.

A steam main 32 having outlets 34 connecting with the interior of the pressure reducing hopper 8 is provided circumferentially around the upper end of the hopper 8 as a precautionary measure. In the event that the burden consists of large size particles of material, steam may then be introduced into the hopper 8 to create a gas seal in the upper portion of the pressure reducing hopper 8 so as to insure continuous operation of the furnace at desired top pressure.

A mass flow surge hopper 36 is disposed on top of and communicates with the pressure reducing hopper 8. The angle of the lower walls of the surge hopper 36 extend preferably upwardly and outwardly at an angle of approximately to the horizontal so as to insure free flow of material out of the surge hopper.

A rotating charging hopper 38 is provided at the top of the surge hopper 36 for distributing the pre-mixed burden material evenly. The rotating charging hopper is fed by an endless belt conveyor 40 which discharges into a chute 42 which, in turn, conducts burden material to the charging hopper. The charging hopper is mounted on rollers 44 which roll along an inner shoulder 46 formed in the upper portion of the surge hopper.

A flip-gate 48 is provided in the chute 42 for diverting material from the chute to another belt conveyor 50 which conducts it to an overflow bin or another blast furnace when it is no longer desired to charge material into the surge hopper. A gate-type valve 52 is attached to the bottom of the chute 42 for sealing the chute when burden material is not being charged into the furnace for any reason.

be utilized in the surge'hopper to control 'the flow rate" of the incoming material from the stock house (not shown).

An emergency bell 54 is suspended by means of a rod 56 from the super-structure of the blast furnace so as to be vertically reciprocable in the restricted upper end of the pressure reducing hopper 8. The bell 54 is adapted to seal off the upper end of the hopper 8 in the event that for any reason the level of burden material threatens to fall below the upper end of the hopper and thus threaten the maintenance of desired top pressure in the blast furnace. A spider support 58 in the lower portion of the surge hopper 36 guides the'bell rod 56 and prevents the bell from being displaced off-center by the burden mate-rial.

In operation, pre-mixed burden material from the stock house is deposited on the belt conveyor 40 and is carried thereby to the chute 42 from whence it is discharged into the rotating charging hopper 38. The charging hopper 38 rotates continuously so asto distribute the pre-mixed burden material evenly in the surge hopper 36. From the surge hopper 36, the material flows continuously into the pressure reducing hopper 8 and from there through the restricted throat 12 into the stack of the furnace. The stack is thus burdened continuously with a pre-mixed burden material.

Although I have shown but one embodiment of my invention, it will be apparent that other adaptations and modifications may be made Without departing from the scope of the following claims.

I claim:

1. In a blast furnace having a vertical stack for receiving and confining burden material to be smelted, the improvement therewith of a top structure comprising a hopper spaced above the top of said stack, a gas collecting main extending around the top of said stack below said hopper, radial gas exhaust means in the bottom of said hopper opening into said main, secondary gas outlets adjacent the top of said hopper, a surge hopper mounted 4' on top of said first-mentioned hopper and communicating therewith, rotary charge distributing means adjacent the top of the surge hopper, and a burden material inlet in the top of the surge hopper discharging into said dis tributing means, said first-mentioned hopper having a restricted upper end and a bell vertically, reciprocable in said restricted upper end adapted to cooperate therewith to stop the flow of=material into said first-mentioned. hopper from said surge hopper. I I I 2. Apparatus as defined by claim 1 in which the side walls of said upper end of said fi rst-mentioned hopper extend downwardly and outwardly "at an angle of approximately degrees to the horizontal. i

3. Apparatus as defined by claim 1 in which the bottom of said first-mentioned hopper is formed wither-restricted annular throat having an entrance angle and an exit angle each greater than 60-degrees and less than 90'degrees to the horizontal. j

'4. Apparatus as defined by claim 1 in which the walls in the lower'portion of said surge hopper extend upwardly and outwardly at an angle of approximately degrees to the horizontal.

5. Apparatus-as defined by claim 1 in whicha steam main is circumferentially disposed around the upper end of said first-mentioned hopper, and radialducts connect said steam main with the upper portion of said firstmentioned hopper.

References Cited 7 UNITED STATES PATENTS 2,194,454 3/ 1940 Greenawalt 266-27; X 2,619,344 11/1952 Mursch 266-31 X 3,131,821 5/1964- Tsujihata et al 214-:35

I SPENCER OVERHOLSER, Primary Examiner JOHN S. BROWN, Assistant-Examiner US. Cl. X.R. 

